Automatic spraying techniques have long been employed for painting large articles such as cars, trucks, refrigerators, etc. The items being sprayed are generally advanced along a conveyor line that passes through a water wash paint spray booth where a fine spray of paint is directed at the articles being painted from spray guns that are located at the sides of the conveyor. Overspray paint, that is, paint that does not contact the article being painted, forms a fine mist of paint in the air space surrounding the painted article. This paint mist must be removed from the air. To accomplish this, the contaminated air is pulled through the paint spray booth by air exhaust fans. A curtain of circulating water is maintained across the path of the air in a manner such that the air must pass through the water curtain to reach the exhaust fans. As the air passes through the water curtain, the paint mist is “scrubbed” from the air and carried to a sump basin usually located below the paint spray booth. In this area, the paint particles are separated from the water so that the water may be recycled and the paint particles disposed of.
Paint is a tacky material and it tends to coagulate and adhere to the spray booth surfaces, particularly in the sump and drain areas, and must constantly be removed from the sump to prevent clogging of the sump drain and recirculating system. In order to assist in the removal of the oversprayed paint from the air and to provide efficient operation of paint spray booths, detackifying agents are commonly employed in the water used in such systems, and are typically incorporated into the water wash recirculated in the paint spray system. Detackifying the paint eliminates or minimizes the adhesive properties, or tackiness, of the paint, thereby preventing the oversprayed paint from adhering to surfaces, such as sump and drain areas.
One of the difficulties with recovering paint overspray in a water wash spray booth as described above is the limited amount of paint that can be incorporated into the water. As such, detackifying agents should have a high load capacity, such that the water wash recirculated through the spray booth can detackify, coagulate and flocculate a high volume of oversprayed paint before exhaustion.
In recent years, the need to reduce solvent emission has resulted in the reduction of solvent-based or solventborne paints, and an increase in the use of water-based or waterborne paints. Because the hydrophilic properties of the waterborne coating compositions render such compositions readily dispersible or soluble in water, removal of paint solids comprised of components such as organic resins, pigments, and organic solvents, from waterborne paint overspray typically requires the use of different detackifying processes in paint spray booths when compared to solvent-based paints.
Accordingly, further improvements would be a welcome addition to the art, wherein compositions and methods useful for removal of paint overspray from both waterborne and solvent-based paints are employed to effectively decrease the amount of one or more of organic resins, pigments, and organic solvents in paint spray booths.